1. Field of the Invention
The present invention relates to a rotary electronic component used for forming input operation portions of various electronic devices.
2. Background Art
An increasing number of rotary electronic components are being mounted in input operation parts of a range of electronic devices. A conventional rotary electronic component is described below with reference to FIGS. 5 to 7. FIGS. 5 and 6 are a sectional view and an exploded perspective view of a conventional rotary electronic component, respectively. FIG. 7 is a perspective view illustrating a state of assembly of a plate spring and an upper case, which are key parts of the rotary electronic component. This rotary electronic component includes lower case 71 formed of insulating resin, rotor 75 made of insulating resin, rotary contact plate 85, upper case 90, metal cover 95, and plate spring 100.
Multiple resilient contacts 73 are attached by insert-molding to the inner bottom face of the cavity of a box-shaped lower case 71 with an open top. Rotor 75 includes columnar operating shaft 76, and round flange 78 integrally provided on a bottom part of operating shaft 76. Flange 78 is housed in the cavity, and rotor 75 is rotatably supported by the inner bottom face of cavity of lower case 71.
Rotary contact plate 85 is configured with conductive metal plates of predetermined patterns, and fixed on the bottom face of flange 78 of rotor 75. Each resilient contact 73 is provided such that it makes resilient contact with rotary contact plate 85. Multiple grooves 80 are formed radially on the top face of flange 78.
Upper case 90 is disposed over lower case 71. Upper case 90 has cylindrical bearing 91 protruding upward at the center thereof. Operating shaft 76 of rotor 75 is inserted through bearing 91, and rotatably retained by the inner circumferential face of bearing 91. Cover 95 is mounted over upper case 90, and its leg parts are caulked to the bottom face of lower case 71 so as to integrate upper case 90 and lower case 71.
Plate spring 100 for generating a clicking feedback is ring-shaped in the top view. Each resilient arm 101 extending in an arc shape is bent at its center to form protrusion 102 having a U-shape and protruding downward.
Flat part 103 is provided between resilient arms 101 of plate spring 100. Each of flat parts 103 is provided with through hole 104. Caulking protrusion 92 provided on the bottom face of upper case 90 shown in FIG. 7 is inserted into each through hole 104. The bottom face of upper case 90 is overlaid on the top faces of two flat parts 103. Then, as shown in FIG. 5, the bottom end of each caulking protrusion 92 is deformed and broadened. This deformation makes plate spring 100 firmly attached onto upper case 90. In this attached state, the bottom face of each protrusion 102 resiliently contacts the inner face of groove 80.
In the conventional rotary electronic component as configured above, rotary contact plate 85 attached onto flange 78 rotates to move relative to multiple resilient contacts 73 when rotor 75 is rotated by rotating operating shaft 76. This outputs a predetermined signal. At the same time, the user is aware of a predetermined clicking feedback when protrusion 102 of plate spring 100 goes over the position between grooves 80, and is fitted in the next groove 80.
As described above, the conventional rotary electronic component gives good clicking feedback that offers ease of operation. However, there still remains a strong demand from product manufacturers for the development of rotary electronic components with better usability. There is particularly strong demand for the development of specifications that confirm the operation state in ways other than the clicking feedback.